Early‐Life Stress: Rodent Models, Lessons and Challenges

Abstract

Prototypical maternal care behaviours in rats. The arched back nursing posture (left) is an active nursing posture characterized by a tented (arched) back. Active sensory input from the mother is crucial for pup neurodevelopment and is provided by the dam in the form of licking and grooming (right). See Companion Website for animation www.wiley.com/go/russell/stress. Why study early-life stress?The early postnatal brain is far from mature and hence the perinatal period represents a critical stage of neural development. During this period, the brain is highly vulnerable to both organizing and disorganizing influences from the environment, including environmental stress. What is perhaps most striking about the influences of early-life stress (ELS) on brain development is how permanent and progressive the deleterious effects can be. Indeed, a relatively brief period of stress occurring during just the first few days of life often has life-long consequences for brain structure and function, ultimately impacting on behaviour and vulnerability to subsequent stress. Understanding the mechanisms for the enduring consequences of ELS on brain function has been Lactating rat in nest nursing her litter (left), and licking/grooming her pups (right)

The Effect of Early Neurological Stimulation on Puppy Welfare in Commercial Breeding Kennels

“…If they perceived the stressor of isolation as more aversive than being approached by a stranger, this could explain why puppies displayed more affiliative behaviors toward the unfamiliar person post-isolation testing, which was also observed in a similar study by Romaniuk et al [2]. This explanation would be consistent with existing knowledge that early experiences shape development, which is one of the underlying principles used to support theories of ENS, as discussed previously, e.g., in [10,22]. Furthermore, it is possible that the change in responses from pre-to post-transport reflected that the puppies experienced more distress after transportation than before and therefore sought comfort from the unfamiliar person, as outlined by Romaniuk et al [2].…”

“…Adverse experiences can influence an organism at any age or developmental stage but may have an especially profound effect during early life. Not only is early life a period of heightened development, but it is also suggested that early life experiences inform the programming of certain functions, such as the stress response, as the organism uses cues present in the early environment to predict what the future environment will be and adapt accordingly [9][10][11].…”